Effect of trans fatty acids on serum lecithin: cholesterol acyltransferase in rats

An investigation was undertaken to study the effect of trans isomers of octadecenoic (18:1) and octadecadienoic (18:2) acids on serum lecithin:cholesterol acyltransferase (LCAT). Male rats of the Wistar strain were fed diets containing 15% fat for 9 months. The fat diets were either hydrogenated fat mixtures containing trans fatty acids, corn oil or lard. At the end of 9 months, rats were killed and serum cholesterol levels and LCAT activity were measured. It was found that free and total serum cholesterol levels were decreased when animals were fed trans fatty acids when compared with animals fed corn oil or lard. Although in vitro studies indicated that the percentage of cholesterol esterified in serum was not affected by the presence of dietary trans fatty acids, LCAT activity generally decreased when trans fatty acids were fed to rats for 9 months. In this study a negative correlation was found between serum free cholesterol and LCAT activity. Depressed total LCAT activity (mumoles of cholesterol esterified per hour per liter of serum) may have been related to a reduced amount of substrate (free cholesterol).